The subject of the invention are novel herbicidal compositions containing N-(phosphonomethyl)glycine or one of its salts and one or more alkyl polyxylosides.
A plant protectant enters into a plant either via the leaves (absorption by the leaves) or via the roots (absorption by the roots). Absorption of an active principle by the leaves is difficult and very poor. Aqeuous solutions of plant protectants frequently have low stability over time or are sparingly compatible with the components which are usually present in the end solutions for plant treatment. The herbicides of the N-(phosphonomethyl)glycine family have been on the market for the several years. European Patent Application EP 0 220 902 discloses herbicidal concentrates containing glyphosate and alkyl polyglycosides.
During its studies with the aim of proposing novel formulations of plant protectants which are less harmful to the environment while being as effective as the prior-art formulations, the applicant company has produced the novel concentrate, which is a subject of the present invention.
Subject of the invention is a composition containing
(a) N-(phosophonomethyl)glycine or one of its salts,
(b) at least one compound of the formula (I):
ROxe2x80x94(X)pxe2x80x83xe2x80x83(I)
in which:
p represents a decimal number between 1 and 5,
X represents the xylose residue, and
R represents a straight-chain or branched, saturated or unsaturated alkyl radical having 6 to 18 carbon atoms,
(c) a dispersing medium for the active principle and compound of the formula (I),
(d) if appropriate one or more other surfactants and
(e) if appropriate one or more inert adjuvants.
Straight-chain or branched, saturated or unsaturated hydrocarbon radical having 6 to 18 carbon atoms is to be understood as meaning, for R, in particular an alkyl radical or an alkenyl radical. R more particularly represents an alkyl radical or an alkenyl radical having 8 to 16 carbon atoms. Examples of the alkyl or alkenyl radical which represents R are those selected from straight-chain or branched hexyl radicals, straight-chain or branched heptyl radicals, straight-chain or branched octyl radicals, straight-chain or branched nonyl radicals, straight-chain or branched decyl radicals, straight-chain or branched decenyl radicals, straight-chain or branched undecyl radicals, straight-chain or branched undecenyl radicals, straight-chain or branched dodecyl radicals, straight-chain or branched tridecyl radicals, straight-chain or branched tetradecyl radicals, straight-chain or branched pentadecyl radicals and straight-chain or branched hexadecyl radicals.
Other examples of branched radicals are those of the formula (II):
CH(CnH2n+1)(CmH2m+1)xe2x80x94CH2xe2x80x94
in which m is an integer between 2 and 18, n is an integer between 2 and 18, and the total n+m is greater than or equal to 6, preferably less than or equal to 14.
The oligomeric structure (X)p can be present in all isomeric forms, whether this is optical isomerism, geometric isomerism or positional isomerism; it can also represent a mixture of isomers.
In formula (I), group Rxe2x80x94Oxe2x80x94 is bound to X by the anomeric carbon of the xylose residue to form an acetal function.
p, which represents the mean degree of polymerization of the saccharide, is more particularly between 1 and 2.5, very particularly between 1 and 2.0.
In a first particular aspect of the present invention, the subject of the invention is a compound of the formula (I) as defined above in which n is less than or equal to 8.
In a second particular aspect of the present invention, the subject of the invention is a compound of the formula (I) as defined above in which m is less than or equal to 6. In this case, R represents more particularly one of the radicals 2-butylhexyl (m=4, n=4), 2-butyldecyl (m=4, n=8) or 2-hexyloctyl (m=6, n=6).
The compounds of the formula (I) as defined above are prepared either by reacting xylose of the formula (III):
HOxe2x80x94Xxe2x80x83xe2x80x83(III)
with an excess of alcohol of the formula (IV):
ROHxe2x80x83xe2x80x83(IV),
and eliminating the fatty alcohol of the formula (IV) which has not reacted,
or by reacting xylose of the formula (III) with an alcohol of the formula (V):
Rxe2x80x94OHxe2x80x83xe2x80x83(V)
in which R1 has 1 to 4 carbon atoms, more particularly with butanol, to give the acetal of the formula (VI):
R1Oxe2x80x94(X)pxe2x80x83xe2x80x83(VI),
which acetal of the formula (VI) subsequently undergoes transacetalization by means of an excess of alcohol of the formula (IV) with distillation of the alcohol of the formula (V) formed followed by elimination of the alcohol of the formula (IV) which has not reacted.
In the process as defined hereinabove, the formation reaction of the compound of the formula (I) is carried out in the presence of strong acidic catalysts, such as, for example, mineral acids such as sulphuric acid, hypophosphorous acid or a mixture of these acids.
The alcohol of the formula (IV) which has not reacted is eliminated by methods known to the skilled worker such as, for example, distillation, thin-film distillation, molecular distillation or solvent extraction.
Dispersing medium of the plant protectant and of the compound(s) of the formula (I) is to be understood as meaning, for the purposes of the present invention, any liquid in which the plant protectant and the compound(s) of the formula (I) are soluble or are dispersed. In the case of glyphosate, the dispersing medium is preferably water.
In addition to the compounds of the formula (I) as defined above, the composition can contain other surfactants conventionally used in herbicidal compositions. These surfactants can be anionic, cationic, non-ionic or amphoteric. Examples of such surfactants are described in WO 99/03343, EP 0 508 022, EP 0 531 269, WO 96/22109 or U.S. Pat. No. 4,557,751.
When such surfactants are present in the composition which is a subject of the present invention, they preferably take the form of ethoxylated fatty acid esters described in WO 96/22109, modified vegetable oils described in WO 00/1233 and/or alkoxylated fatty amines described in U.S. Pat No.4,557,751. The contents of the publications WO 96/22109, WO 00/1233 and U.S. Pat. No. 4,557,751 are an integral part of the present description.
When inert adjuvants are present in the composition which is a subject of the present invention, they take the form of, for example, absorbers of ultraviolet rays.
Modified or unmodified vegetable oils which can be mentioned are, more particularly, sunflower oil, linseed oil, soya oil, corn oil, peanut oil, coconut oil, olive oil, palm oil, hydrogenated palm oil or rapeseed oil, either modified or unmodified.
Glyphosphate, or N-(phosphonomethyl)glycine, which is present in the composition can be in free form or in salt form, preferably in the form of a water-soluble salt, such as, for example, monoisopropylamine or trimethylsulphonium salts.
A subject of the invention is a plant-protective treatment method, characterized in that the composition as defined above is used.
The composition is either ready-to-use or in the form of a concentrate which is previously dissolved or dispersed in the water before being sprayed onto the area to be treated, for the preparation of a composition for the plant-protective treatment of plants, in particular in agriculture or for treating ornamental gardens. The dilution rate depends essentially on the minimal effective quantity of the crop protectant required, which is expressed in weight per area to be treated.
As shown in the experimental study described hereinbelow, replacing alkyl polyglucoside compounds by alkyl polyxylosides with the same side chain significantly improves the herbicidal activity of the formulation and thus allows thus the use of less glyphosate per hectare to be treated.